Slow-release formulations of 5-hydroxytryptophan as an adjunct to pro-serotonergic therapies

ABSTRACT

The present invention concerns the treatment of serotonergic dysregulation disordersand/or augmentation of serotonin levels in the brain by add-on treatments to serotonin enhancers, and slow-release formulations of 5-hydroxytryptophan (5-HTP) therefor.

RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. §119(e) of U.S.Provisional Patent Application Ser. No. 61/405,831, filed Oct. 22, 2010,and U.S. Provisional Patent Application Ser. No. 61/504,354, filed Jul.5, 2011, the disclosure of each of which is incorporated herein byreference in its entirety.

STATEMENT OF GOVERNMENT SUPPORT

This invention was made with Government support under grant numberMH79201 from the National Institutes of Health. The United StatesGovernment has certain rights in this invention.

FIELD OF THE INVENTION

The present invention concerns the treatment of psychiatric disorders,serotonergic dysregulation disorders and/or augmentation of serotoninlevels in the brain, and formulations of 5-hydroxytryptophan usefultherefor.

BACKGROUND OF THE INVENTION

Dysregulation of serotonergic (or 5-hydroxytryptamine, 5-HT)neurotransmission is believed to be an important contributing factor innumerous psychiatric disorders, including major depression,attention-deficit/hyperactivity disorder (ADHD), schizophrenia,aggression and suicidal behavior. The central serotonergic system isalso a primary target for clinical treatment of these disorders. Drugsthat target this system include tricyclic antidepressants and serotoninreuptake inhibitors (e.g., SSRIs), as well as psychostimulants andhallucinogenic drugs (see, e.g., Bonasera et al., Pharmacol. Ther. 88,133 (2000); Gingrich et al., Psychopharmacol. 155, 1 (2001); Murphy etal., Genes Brain Behav. 2, 350 (2003)).

In depression, for example, serotonergic neurotransmission deficiencieshave been prominently implicated for more than 40 years. While itremains to be definitively proven that 5-HT deficiency can causedepression, biomarker and post-mortem studies indicate that serotonindeficiency exists in at least some depression patients (Jacobsen et al.,Deficient serotonin neurotransmission and depression-like serotoninbiomarker alterations in tryptophan hydroxylase 2 (Tph2)loss-of-function mice. Molecular psychiatry (May 3, 2011); Meltzer,Serotonergic dysfunction in depression. Br J Psychiatry Suppl, 25(1989); Asberg, Neurotransmitters and suicidal behavior. The evidencefrom cerebrospinal fluid studies. Ann N Y Acad Sci 836, 158 (1997);Correa et al., Prolactin response to D-fenfluramine and suicidalbehavior in depressed patients. Psychiatry Res 93, 189 (2000)).

On the other hand, it is beyond dispute that drugs that enhance theextracellular level of serotonin treat depression symptoms, at least inmoderate to severe cases (Kirsch, I. et al. Initial severity andantidepressant benefits: a meta-analysis of data submitted to the Foodand Drug Administration. PLoS Med 5, e45, 2008).

However, drugs that enhance serotonin extracellular levels in the brain,such as selective serotonin reuptake inhibitors (SSRIs), alleviatedepression symptoms only in about 50% of patients, leaving a largetreatment-resistant depression (TRD) population (Fava, Diagnosis anddefinition of treatment-resistant depression. Biological psychiatry 53,649 (2003)). Add-on of a second serotonin enhancing agent to SSRItreatment may augment clinical efficacy (Blier et al., Mirtazapine andparoxetine in major depression: a comparison of monotherapy versus theircombination from treatment initiation. Eur Neuropsychopharmacol 19, 457(2009); Blier et al., Potential mechanisms of action of atypicalantipsychotic medications in treatment-resistant depression and anxiety.J Clin Psychiatry 66 Suppl 8, 30 (2005)), indicating that insufficientincrease of extracellular serotonin levels may be causal in at leastsome SSRI TRD.

SUMMARY OF THE INVENTION

Provided herein is 5-HTP included in or provided as slow-releaseformulations (e.g., delayed release formulation, sustained releaseformulation, drug depot formulation, etc.), which are useful to improvethe drugability of 5-HTP as well as improve the efficacy ofpro-serotonergic medications in the treatment of psychiatric and otherdisorders related to serotonin dysregulation.

Also provided are methods of treating a subject for a serotonergicneurotransmission dysregulation disorder including administering to saidsubject 5-hydroxytryptophan (5-HTP) at a slow rate. In some embodiments,the 5-HTP is administered in combination with a serotonin enhancer, said5-HTP administered in an amount effective to enhance the effects of theserotonin enhancer. In some embodiments, the subject in being treatedwith a serotonin enhancer (e.g., subject has been treated with theserotonin enhancer for at least 2, 3 or 4 weeks).

In some embodiments, the 5-HTP is provided in an amount effective toincrease extracellular levels of serotonin in the brain as compared tothe levels upon serotonin enhancer treatment without the 5-HTPadministration.

In some embodiments, the 5-HTP is provided in or as an oral formulation.In some embodiments, the 5-HTP is provided in or as a transdermalformulation.

Also provided is a formulation such as a patch for transdermaladministration comprising: a) a backing; and b) a drug layer comprising5-hydroxytryptophan (5-HTP), or a pharmaceutically acceptable salt orprodrug thereof; said patch configured to administer said 5-HTPtransdermally. In some embodiments, the patch is a single-layerdrug-in-adhesive patch, a multi-layer drug-in-adhesive patch, areservoir-type patch, a matrix-type patch or a monolithic patch.

Further provided is 5-HTP included in or provided as slow-releaseformulation for use in the treatment of a serotonergic neurotransmissiondysregulation disorder. In some embodiments, the 5-HTP is included in orprovided as a slow-release formulation for use as an adjunct (add-on) toa serotonin enhancer therapy. Also provided is the use of a 5-HTPformulation as provided herein in the manufacture of a medicament forthe treatment of a serotonergic dysregulation disorder (e.g., as anadjunct to a serotonin enhancer therapy).

The foregoing and other objects and aspects of the present invention areexplained in greater detail in the drawings herein and the specificationset forth below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1. 5-HTP in drinking water (4 mg/ml≈320 mg/kg/day, no carbidopa)restores brain 5-HT in 5-HT deficient mice

FIGS. 2A-2B. Body weight decrease observed after 5-HTP 4 mg/ml (FIG.2A). No diarrhea and no obvious malaise were observed, so the decreaseis likely due to decreased drinking (FIG. 2B).

FIGS. 3A-3C. Decreased drinking observed coincides with the body weightdecrease observed after 5-HTP administered at 2 mg/ml and 4 mg/ml.

FIG. 4. Administration by bolus injection of 5-HTP 120 mg/kg i.p. causeddiarrhea and obvious malaise. A score of 0=absence; 1=trace; and2=obvious/severe.

FIGS. 5A-5C. No toxicity was observed as reflected by weights (5A, 5B),head twitches and diarrhea (not shown), upon administration of oral5-HTP (≈200 mg/kg/day (5C), no carbidopa) as an add-on to existingFluoxetine (≈18 mg/kg/day (5C)).

FIGS. 6A-6B. Serotonin syndrome-like behavior was observed uponadministration of an acute 5-HTP bolus (80 mg/kg, i.p.) as an add-on toexisting Fluoxetine (FLX) (≈18 mg/kg/day) (6A, 6B). However, FLXunexpectedly appeared to lessen 5-HTP-induced diarrhea when assessed byscoring the presence of peri-rectal fecal smearing (6B).

FIG. 7. Wild-type mice showed a robust increase in extracellularserotonin levels (5-HT_(Ext)) in response to chronic FLX (≈48mg/kg/day). Tph2 R439H mice had much lower baseline 5-HT_(Ext), andfollowing FLX the 5-HT_(Ext) levels were only enhanced to levelsslightly below baseline levels in WT mice.

FIG. 8. Five days add-on of 5-HTP SR (˜100 mg/kg/day) to chronic FLX(≈18 mg/kg/day) in Tph2 R439H mice produced an 8-fold increase in5-HT_(Ext), as compared to FLX+vehicle treated mice, bringing the5-HT_(Ext) close to levels seen in FLX treated WT mice.

FIGS. 9A-9B. 5-HTP SR in the delivered dose (˜100 mg/kg/day) added on tochronic FLX (≈18 mg/kg/day) in WT mice produced no signs of toxicity,i.e. body weight changes of the first 4 days of treatment (9A) or 5-HTsyndrome-like behaviors upon treatment initiation (9B).

FIGS. 10A-10G. Subcutaneous (sc) administration of 5-HTP enhanced the5-HT_(Ext) response to chronic fluoxetine (FLX) and increased 5-HTtissue levels in mice not treated with FLX. 10A: 5-HTP SR (100 mg/kg/d)two-fold enhanced the 5-HT_(Ext) response to chronic FLX in WT mice atbaseline and following neuronal depolarization with K⁺. 10B: 5-HTP SRseven-fold enhanced the 5-HT_(Ext) response to chronic FLX in Tph2KImice, a mouse model of 5-HT deficiency, at baseline and followingneuronal depolarization with K⁺. Note x-axis scale differences between10A and 10B. 10C: For reference, while chronic FLX fold-wise enhanced5-HT_(Ext) similarly in WT and Tph2KI mice, the levels of FLX treatedTph2KI mice barely reached the levels of untreated WT. 10D-10E: 5-HTP SRincreased tissue 5-HT (10D) and 5-HIAA (10E) in both genotypes. 10E-10G:5-HTP IR (50 mg/kg, sc 8 h post-injection, after 4 d of 2×50 mg/kg)increased tissue 5-HT in Tph2KI mice (10F), but caused a small 5-HTdecrease at this time point in WT mice. A small increase in 5-HIAAlevels were also observed in Tph2KI mice (10G). *, p<0.05, vehicle vs5-HTP or vehicle vs FLX C). #, p<0.05, WT vs Tph2KI, C), T-test. N-7-10,microdialysis. N=4-6, tissue 5-HT and 5-HIAA.

FIGS. 11A-11L. Virtually no 5-HT associated side-effects in response toSC 5-HTP SR treatment in mice maintained on chronic FLX. 11A-11D: Day oftreatment start. No occurrence of diarrhea (11A), tremor (11B) ortemperature changes (11C) but perhaps a slight, non-significant increasein splaying in the Tph2KI mice (11D) in response to 5-HTP SR. 11E-11I:Day 2-4 of treatment: No occurrence of diarrhea (11E), tremor (11F),temperature changes (11G) or abnormal splaying (11H), but a transientdecrease in body weight (11I) in the Tph2KI mice only at day1. 11J-11L:Day 5: No effect on locomotor and anxiety-like behavior in the openfield. *, p<0.05, WT, vehvs 5-HTP. @, p<0.05, Tph2PKI, vehvs 5-HTP,T-test or 2way RM-ANOVA. N=4-6

FIGS. 12A-12I. Marked 5-HT associated side-effects in response to 5-HTPimmediate release (IR) (2×50 mg/kg/day, S.C.) in mice maintained onchronic FLX. 12A-12F: 5-HT side-effects followed over first 4 days oftreatment following AM 5-HTP IR administration. 5-HTP IR caused markedoccurrence of diarrhea (12A), tremor (12B), hypothermia (12C), splaying(12D) and head-twitches (12F). Body Weights were only minorly andtransiently affected in Tph2KI mice (12E). 12G-12I: Day 5: 5-HTP IRsuppressed locomotion and increased anxiety-like behaviors in the openfield in Tph2KI mice, while in WT mice only vertical activity wassignificantly suppressed, although a trend for suppression was observedfor total distance. *, p<0.05, WT, vehvs 5-HTP. @, p<0.05, Tph2PKI,vehvs 5-HTP. T-test or 2way RM-ANOVA. N=4-6.

FIGS. 13A-13F. Oral 5-HTP SR (˜250 mg/kg/d) increases 5-HT storage in5-HT deficient Tph2KI mice in the absence of obvious side-effects. 13A:Daily oral 5-HTP dose achieved over 21 days. 13B: No change in bodyweights during 21 days of oral 5-HTP SR treatment. 13C: Increase in 5-HTstorage as measured at noon after 21 days of oral 5-HTP SR treatment.13D: Increased 5-HIAA (5-HT metabolite) tissue levels as measured atnoon after 21 days of oral 5-HTP SR treatment. 13E, 13F: No change innovel open field locomotor activity after 14 days of oral 5-HTP SRtreatment.*, p<0.05, WT, ctrl vs 5-HTP, t-test. @, Tph2KI, ctrl vs5-HTP, t-test.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is explained in greater detail below. Thedisclosures of all references cited herein are incorporated by referenceto the extent they are consistent with the description presented herein.

A. 5-HTP Slow-Release Formulations

“5-hydroxytryptophan” or “5-HTP” is the precursor of serotonin (5-HT) inthe body. Though known as a dietary supplement and experimentally usedin the treatment of depression, appropriate, well-controlled studies of5-HTP antidepressant efficacy are lacking. Indeed, preclinical studiesindicate that 5-HTP administration alone has surprisingly small effectson extracellular serotonin. However, 5-HTP appears to augment theextracellular serotonin response to acute SSRI treatment (Perry, K. W. &Fuller, R. W. Extracellular 5-hydroxytryptamine concentration in rathypothalamus after administration of fluoxetine plusL-5-hydroxytryptophan. J Pharm Pharmacol 45, 759-761 (1993); Jacobsen,J. P. et al. Insensitivity of NMRI mice to selective serotonin reuptakeinhibitors in the tail suspension test can be reversed by co-treatmentwith 5-hydroxytryptophan. Psychopharmacology 199, 137-150, (2008))[cite?] In addition, administration of 5-HTP can lead to side effects(e.g., gastrointenstinal effects such as nausea, vomiting and diarrhea),dizziness, euphoria and mood changes, typically upon administration(Turner, E. H., Loftis, J. M. & Blackwell, A. D. Serotonin a la carte:supplementation with the serotonin precursor 5-hydroxytryptophan.Pharmacol Ther 109, 325-338, (2006)).

This may to due to 5-HTP's rapid absorption-elimination profile (GijsmanH. J. et al. Placebo-controlled comparison of three dose-regimens of5-hydroxytryptophan challenge test in healthy volunteers. J ClinPsychopharmacol. April; 22(2):183-9 (2002))., which conceivably canresult in overdose upon administration followed by withdrawal upon quickelimination in the body. This aspect, the above mentioned moderateeffect of 5-HTP alone on extracellular 5-HT combined with theavailability of alternatives to enhance extracellular serotonin levels,can explain its limited use in the clinical setting.

As used herein, “slow-release 5-HTP” refers to a formulation with theability to release 5-HTP at a slow rate, such that the plasma T_(1/2) isdelayed and/or T_(max) is decreased as compared to an immediate releaseformulation. The terms “5-HTP at a slow rate” and “5-HTP at a slowrelease” are used interchangeably and refer to the ability to cause the5-HTP to be released in the subject at a slower rate than ifadministered directly.

In some embodiments, the slow-release formulation comprises 5-HTP in oras a delayed release formulation, sustained release formulation and/ordrug depot formulation. See, e.g., U.S. Pat. No. 8,029,822 to Faour etal.; U.S. Pat. No. 8,021,687 to Hirsh et al.; U.S. Pat. No. 8,017,152 toGustafsson et al.; U.S. Pat. No. 8,007,826 to Blight et al.; U.S. Pat.No. 7,914,804 to O'Neil et al.; U.S. Pat. No. 7,906,141 to Ziegler etal.; U.S. Pat. No. 7,897,173 to Ziegler et al.; U.S. Pat. No. 7,964,215to Ganesan et al.; U.S. Pat. No. 7,709,024 to Kadum et al.; U.S. Pat.No. 7,741,273 to McKay; U.S. Pat. No. 7,645,460 to Dansereau et al.; andU.S. Pat. No. 5,658,587 to Santus et al., which are incorporated byreference herein.

“Sustained release” formulations release drug at a predetermined rateand/or release in a manner that maintains the drug as a substantiallyconstant level (e.g., plasma level) for a set period of time. Examplesof sustained release formulations include, but are not limited to, oralformulations (e.g., enteral, buccal/sublabial/sublingual, respiratory),ocular/otologic/nasal formulations, dermal formulations (e.g., ointment,paste, film, hydrogel, liposomes, dermal patch, transdermal patch,transdermal spray), injection/infusion (e.g., intradermal, subcutaneous,transdermal implant, intramuscular).

In some embodiments, the slow-release formulation employs agastro-retentive principle, delivering the 5-HTP in a slow release inthe ventricle and/or upper intestine using for instance buoyant systems,high density systems, magnetic systems, mucoadhesive systems,swelling/expanding systems, superporous hydrogels and systems utilizingthe inclusion of gastric motility retarding agents with biocompatiblepolymeric materials (Murphy C. S. et al. Gastroretentive drug deliverysystems: current developments in novel system design and evaluation.Curr Drug Deliv. October; 6(5):451-60 (2009)).

In some embodiments, the slow-release formulation employs oralhydrophilic or lipophilic matrix tablets. In some embodiments, theslow-release formulation employs oral osmotic systems, for instance theasymmetric membrane technology or swellable core technology. In someembodiments, the slow-release formulation employs oral multiparticulatesystems (Thombre A G. Assessment of the feasibility of oral controlledrelease in an exploratory development setting. Drug Discov Today.September 1; 10(17):1159-66 (2005)).

For example, immediate-release oral 5-HTP typically has a T_(1/2) of 2-3hours, and thus a 5-HTP at a slow rate would have a T_(1/2) greater than3, 4, 5, 6 or 7 hours. In some embodiments, the T_(1/2) is at least 8hours. In some embodiments, the T_(1/2) is from 8, 10 or 12 hours to 24,48 or 72 hours.

As another example, immediate-release oral 5-HTP has a T_(max) of 1-2hours. Thus, in some embodiments, the slow-release 5-HTP is administeredand/or formulated such that the T_(max) (time of maximal plasmaconcentration after administration) of 5-HTP is at least 2 hours, orbetween 2 hours and 12 hours.

In some embodiments, 5-HTP is provided in a therapeutically effectiveamount in a formulation suitable for oral administration. As usedherein, the term “therapeutically effective amount” refers to thatamount of compound that is sufficient to show a benefit in the subject.In some embodiments, the formulation is provided in a unit dose foronce-daily or twice-daily use. See U.S. Patent application publicationno. 2010/0298379 to Jacobsen et al., which is incorporated by referenceherein in its entirety.

In some embodiments, a daily dose of 0.05 to 10 grams may be provided(e.g., as one tablet for daily dosing, or two tablets for twice-dailydosing with half the daily dosage in each). In some embodiments, thedaily dose may be from 0.01, 0.05, 0.1, 0.2, 0.5, or 0.75, to 5, 8, or10 grams per day. In some embodiments, the daily dose may be from 1 to 5grams per day. In some embodiments, the daily dose may be from 1 to 3grams per day.

In some embodiments, 5-HTP is administered so as to achieve plasma 5-HTPlevels averaging 10-100 ng/ml. In some embodiments, 5-HTP isadministered so as to achieve plasma 5-HTP levels averaging 100-1000ng/ml.

In a particular embodiment, 5-HTP is provided in a formulation suitablefor transdermal administration. In some embodiments, the formulation issuitable for 1, 2, 3, 5, 7, 10, 12, 14, or 30-day transdermaladministration. In some embodiments, transdermal administration may havethe advantage that gastrointestinal (GI) 5-HT formation is reduced,thereby lessening GI side effects (common from 5-HTP and otherpro-serotonergic compounds). Transdermal administration may, therefore,allow for higher plasma 5-HTP levels without the occurrence ofsignificant GI side effects and achieve better efficacy.

In some embodiments, 5-HTP, a pharmaceutically acceptable salt, orprodrug thereof, is formulated for transdermal administration. In someembodiments, the formulation is in the form of a “patch.” The patch maybe a single-layer drug-in-adhesive patch, a multi-layer drug-in-adhesivepatch (typically also including a membrane such as a rate-controllingmembrane between at least two of the layers), a reservoir-type patch, amatrix-type or monolithic patch, etc.

In some embodiments, the patch includes a backing, an adhesive druglayer, and a release liner. In some embodiments, the patch furtherincludes a second adhesive layer (with or without drug), and in someembodiments a membrane (e.g., a rate-controlling membrane) is positionedbetween a first and second adhesive layer. See also US PatentApplication Publication nos. 2003/0109512 to Kucharchuk et al. and2005/0163831 to Ikesue et al., which are each incorporated by referenceherein.

For embodiments including a backing, any backing may be used withoutparticular limitation, and a stretchable or an unstretchable backing maybe used. Specific examples of the backing include cloth, nonwoven cloth,polyurethane, polyester, polyvinyl acetate, polyvinylidene chloride,polyethylene, polyethylene terephthalate and aluminum sheet, one made ofcomplex material thereof, and the like.

In some embodiments, an adhesive layer comprising an adhesive base agentand 5-HTP may be placed on the backing. The amount of 5-HTP in someembodiments is 0.1-50 weight % of the total weight in the adhesivelayer. In some embodiments the adhesive layer may include an adhesiveagent such as a rubber polymer, an acrylic polymer, or a combinationthereof. In some embodiments the base adhesive agent is 10-90 weight %of the total weight of the adhesive layer.

Examples of rubber polymers include, but are not limited to,styrene-isoprene-styrene copolymer, polyisobutylene, isoprene rubber,styrene-butadiene-styrene copolymer, styrene-butadiene rubber andsilicone rubber. These polymers may be used individually or incombination. Examples of acrylic polymers include, but are not limitedto, polymers employing alkyl (meth)acrylate esters in which carbonnumber in the alkyl group is 4 or more and/or 15 or less. Specificexamples of such alkyl (meth)acrylate ester include alkyl (meth)acrylateesters having a linear alkyl group, a branched alkyl group such asbutyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl andtridecyl. These polymers may be used individually or in combination.

Further, a copolymerizable monomer may be copolymerized in the alkyl(meth)acrylate ester, if desired. Examples of the monomer includecarboxyl group containing monomers such as (meth)acrylic acid, itaconicacid, maleic acid or maleic anhydride; sulfoxyl group containingmonomers such as styrenesulfonate, allylsulfonate,sulfopropyl(meth)acrylate, (meth)acryloyloxynaphthalenesulfonic acid oracrylamide methylpropanesulfonic acid; hydroxyl group containingmonomers such as hydroxyethyl (meth)acrylate ester or hydroxypropyl(meth)acrylate ester; amide group containing monomers such as(meth)acrylamide, dimethyl(meth)acrylamide, N-butylacrylamide,N-methylol(meth)acrylamide or N-methylolpropane (meth) acrylamide;alkylaminoalkyl group containing monomers such as aminoethyl(meth)acrylate ester, dimethylaminoethyl (meth)acrylate ester ortert-butylaminoethyl (meth)acrylate ester; alkoxyalkyl (meth)acrylateesters such as methoxyethyl (meth)acrylate ester or ethoxyethyl(meth)acrylate ester; an alkoxy group (or ether bond in a side chain)containing (meth)acrylic esters such as tetrahydrofurfuryl(meth)acrylate ester, methoxyethylene glycol (meth)acrylate ester,methoxydiethylene glycol (meth)acrylate ester, methoxypolyethyleneglycol (meth)acrylate ester or methoxypolypropylene glycol(meth)acrylate ester; and vinyl-series monomers such as(meth)acrylonitrile, vinyl acetate, vinyl propionate,N-vinyl-2-pyrrolidone, methylvinyl pyrrolidone, vinyl pyridine, vinylpiperidone, vinyl pyrimidine, vinyl piperazine, vinyl pyrazine, vinylpyrrole, vinyl imidazole, vinyl caprolactam, vinyl oxazole and vinylmorpholine. One kind of or two kinds or more in combination of these maybe copolymerized. These copolymerizable monomers can be used for thepurpose of adjusting cohesion force of the adhesive layer or enhancingsolubility of the drug. The copolymerization amount may be within arange of 2-40% by weight according to some embodiments.

In some embodiments, the adhesive layer may include as a permeationenhancer compounds that are conventionally recognized to have apermeation enhancing effect on the skin. Examples include, but are notlimited to, fatty acids having 6 to 20 carbon atoms, aliphatic alcohols,fatty acid esters, fatty acid amides, and fatty acid ethers, aromaticorganic acids, aromatic alcohols, aromatic organic acid esters andethers, which may be saturated or unsaturated, and also may be linear,branched or cyclic, lactic acid esters, acetic acid esters,monoterpenes, sesquiterpenes, Azone, Azone derivatives, glycerin fattyacid esters, propylene glycol fatty acid esters, sorbitan fatty acidesters (Span), polysorbates (Tween), polyethylene glycol fatty acidesters, polyoxyethylene hydrogenated castor oils (HCO), polyoxyethylenealkyl ethers, sucrose fatty acid esters and vegetable oils. Examplesinclude caprylic acid, capric acid, caproic acid, lauric acid, myristicacid, palmitic acid, stearic acid, isostearic acid, oleic acid, linoleicacid, linolenic acid, lauryl alcohol, myristyl alcohol, oleyl alcohol,isostearyl alcohol, cetyl alcohol, methyl laurate, hexyl laurate, lauricacid diethanol amide, isopropyl myristate, myristyl myristate,octyldodecyl myristate, cetyl palmitate, salicylic acid, methylsalicylate, ethylene glycol salicylate, cinnamic acid, methyl cinnamate,cresol, cetyl lactate, lauryl lactate, ethyl acetate, propyl acetate,geraniol, thymol, eugenol, terpineol, L-menthol, borneol, d-limonene,isoeugenol, isoborneol, nerol, dl-camphor, glycerin monocaprirate,glycerin monocaprate, glycerin monolaurate, glycerin monooleate,sorbitan monolaurate, sucrose monolaurate, polysorbate 20, propyleneglycol, propylene glycol monolaurate, polyethylene glycol monolaurate,polyethylene glycol monostearate, polyoxyethylene lauryl ether, HCO-60,pirotiodecane and olive oil. Such permeation enhancers may be used aloneor in combination. In some embodiments, the permeation enhancer ispresent in a range of 0.1 to 10 or 20 weight % of the total weight ofthe adhesive layer.

In some embodiments, the adhesive layer may include a plasticizer.Examples include, but are not limited to, petroleum oil (paraffinprocess oil, naphthene process oil, aromatic process oil and the like),squalane, squalene, vegetable oil (olive oil, camellia oil, castor oil,tall oil, peanut oil and the like), silicone oil, dibasic acid ester(dibutyl phthalate, dioctyl phthalate and the like), liquid rubber(polybutene, liquid isoprene rubber and the like), liquid fatty acidester (isopropyl myristate, hexyl laurate, diethyl sebacate, diisopropylsebacate and the like), polyhydric alcohol (diethylene glycol,polyethylene glycol, glycol salicylate, propylene glycol, dipropyleneglycol and the like), triacetin, triethyl citrate, crotamiton and thelike. Among these plasticizers, polyhydric alcohols, liquid paraffin,liquid polybutene, crotamiton, diethyl sebacate and hexyl laurate aremore preferable, and polyethylene glycol is especially preferable. Theseplasticizers may be used alone or in combination.

In some embodiments, the formulation contains only 5-HTP as primary orthe only active ingredient in the patch.

In some embodiments, administration of 5-HTP is subject to the provisothat the subject is not also concurrently administered a peripheraldecarboxylase inhibitor. In some embodiments, such concurrentadministration have been found to unexpectedly increase rather thandecrease side effects, while having no obvious clinical benefit, despitedecreasing 5-HTP peripheral degradation and enhancing 5-HTP plasmalevels. Peripheral decarboxylase inhibitors include carbidopa,benserazide, methyldopa, etc. See, e.g., U.S. Pat. No. 6,387,936.

In some embodiments, administration of 5-HTP is subject to the provisothat a steroidal drug such as testosterone, estrogen, progesterone,etc., is not administered in combination therewith.

B. Use of 5-HTP Slow-Release Formulation as an Adjunct toPro-Serotonergic Therapies

The 5-HTP formulations taught herein according to some embodiments areuseful in the treatment of a psychiatric disorder/serotonergicneurotransmission dysregulation disorder. In some embodiments, the 5-HTPis used as an adjunct therapy and is administered in combination with aserotonin enhancer such as an S SRI, MAOI, TCA, etc.

“Serotonergic neurotransmission dysregulation disorder” as used hereinrefers to any disorder in which a decrease in available serotonin isbelieved to contribute, at least in part, to a disease, disorder, orcondition and/or is treatable by enhancing serotonergicneurotransmission. Examples of such disorders include, but are notlimited to, depressive disorder (e.g., major depression), anxietydisorder, social anxiety disorder, generalized anxiety disorder, bipolardisorder, schizophrenia, autism, epilepsy, mood disorders, alcohol orsubstance abuse and associated disorders, panic disorder, migraine,tension headache, obesity, bulimia, anorexia, premenstrual syndrome,menopause, sleep disorders (e.g., sleep apnea, narcolepsy, insomnia),attention-deficit/hyperactivity disorder (ADHD), Tourette syndrome,aggression, obsessive compulsive disorder, pathological gambling,novelty seeking, borderline personality disorders, antisocialpersonality disorder, suicidality, eating disorders, sexual dysfunction,dementia, social phobia, fibromyalgia, overactive bladder, chronicfatigue syndrome, chronic pain, sudden infant death syndrome,post-traumatic stress syndrome, and Alzheimer's disease. These termshave their usual meaning in the art (see, e.g., DSM-IV), and referencethereto includes the display of one or more symptoms of the disorder aswell as a formal diagnosis of the same.

In some embodiments, the serotonergic neurotransmission dysregulationdisorder is depression, anxiety, suicidality, obsessive compulsivedisorder (OCD), or attention deficit hyperactivity disorder (ADHD).

“Depressive disorder” or “depression” is a mood disorder in whichfeelings of sadness, loss, anger, or frustration interfere with everydaylife for a significant period of time. Depression may be caused bychemical imbalances in the brain, which may in some instances behereditary. Depression may also be precipitated by events in a person'slife. Symptoms of depression may include one or more of: agitation,restlessness, and irritability; a significant change in appetite, oftenwith weight gain or loss; difficulty concentrating; fatigue and lack ofenergy; feelings of hopelessness and helplessness, or feelings or angeror discouragement; feelings of worthlessness, self-hate, andinappropriate guilt; inactivity and withdrawal from usual activities, aloss of interest or pleasure in activities that were once enjoyed;thoughts of death or suicide; trouble sleeping or excessive sleeping.

“Major depressive disorder” or “major depression” (also called “unipolardepression” or “unipolar major depression”) as used herein has its usualmeaning in the art, and is typically characterized by the presence of atleast five of the depression symptoms noted above for at least twoweeks.

“Treatment-resistant depression” or “TRD” is depression that is nottreated to remission by an antidepressant (e.g., an SSRI/SNRIs), i.e.,typically operationally defined as not treated to remission after twoadequate trials of antidepressants (Fava, M. Diagnosis and definition oftreatment-resistant depression. Biological Psychiatry 53, 649-659,(2003)). This may include an absence or minimal improvement in symptomsupon treatment (e.g., with continuing treatment for more than 4, 5, 6,7, or 8 weeks), an improvement but later recurrence of symptoms despitecontinuing treatment, etc.

“Anxiety disorder” or “anxiety” is abnormal or pathological fear orphobia, and may be continuous or episodic. Symptoms of anxiety mayinclude one or more of: mental apprehension, physical tension, andphysical symptoms such as panic attacks or symptoms associated withhyperventilation.

“Suicidality” is the intention of taking one's life. Factors which maybe considered in making a diagnosis include one or more of: thepatient's history, including a history of previous attempts or a familyhistory of suicide; answers during clinical interview in which thesubject is asked whether they are presently thinking of suicide, whetherthey have made actual plans to do so, whether they have thought aboutthe means, and/or what they think their suicide will accomplish; asuicide note, if any; information from friends or relatives; outcomes ofpsychiatric tests such as the Beck Depression Inventory (BDI), theDepression Screening Questionnaire, and the Hamilton Depression RatingScale; and the patient's mood, appearance, vocal tone, and similarfactors.

“Obsessive compulsive disorder” is a type of anxiety disorder primarilycharacterized by repetitive obsessions (distressing, persistent, andintrusive thoughts or images) and/or compulsions (urges to performspecific acts or rituals). Often the process is entirely illogicaland/or inexplicable. For example, a compulsion of walking in a certainpattern may be used to alleviate an obsession of impending harm.

“Attention deficit hyperactivity disorder” is an abnormal problem(considering the normal range based on a subject's age and development)with inattentiveness, over-activity, and/or impulsivity. Though thecause of ADHD is unknown, imaging studies of the brains of children withADHD suggest that there may be an imbalance of neurotransmitters (e.g.,dopamine, serotonin, and adrenaline) associated with the disorder.

“Substance abuse” as used herein has its usual meaning and includes bothalcohol abuse or addiction (e.g., alcoholism, or alcoholic subjects), aswell as abuse or addiction to drugs such as narcotics, opiates,stimulants, depressants, etc. (e.g., barbiturates, ecstasy, cocaine,crack cocaine, morphine, heroin, amphetamine, methamphetamine,oxycontin, etc.).

There is some evidence in the literature of the effectiveness of 5-HTPas an add-on treatment in depression. For example, Nardini et al.assigned 26 inpatients to clomipramine 50 mg+placebo orclomipramine+5-HTP 300 mg for four weeks; double-blind scoring usingHAMD. A lenient statistical approach was applied to get significances,but it seems fairly clear that 5-HTP enhanced clomipramines effect.Dosing schedule and side effects was not reported upon (Nardini M et al.Treatment of depression with L-5-hydroxytryptophan combined withchlorimipramine, a double-blind study. Int J Clin Pharmacol Res.;3(4):239-50. (1983)). Alino et al. assigned 30 inpatients to nialamid (aMAOI) 300 mg+placebo or nialamid+5-HTP 300 mg for two weeks;double-blind scoring using HAMD. 5-HTP+nialamid were significantlybetter than nialamide alone at endpoint. Twice daily dosing was used.Side effects were “typical of ADs” and severity did not differ betweenthe groups (Aliño J. J. et al. 5-Hydroxytryptophan (5-HTP) and a MAOI(nialamide) in the treatment of depressions. A double-blind controlledstudy. Int Pharmacopsychiatry. 11(1):8-15 (1976)). van Heile treated 99chronic treatment resistant out-patients, mostly on TCAs, with add-on5-HTP ˜200 mg+the PDI carbidopa in a open label add-on study.Forty-three patients went into remission. Once (5-HTP) and thrice(carbidopa) daily dosing was used. Side effects were nausea, vomitingand diarrhea, but the severity was greatly decreased when enteric coated5-HTP capsules were used (van Hiele L J. 1-5-Hydroxytryptophan indepression: the first substitution therapy in psychiatry? The treatmentof 99 out-patients with ‘therapy-resistant’ depressions.Neuropsychobiology. 6 (4):230-40 (1980)). van Praag treated 7 chronictreatment resistant out-patients with clomipramine 50 mg+with 5-HTP˜2-400 mg+the PDI MK 486. Four patients improved, two dropped out due toGI symptoms, one had no change. Dosing schedule was not reported (vanPraag H. M. et al. 5-hydroxytryptophan in combination with clomipraminein “therapy-resistant” depressions. Psychopharmacologia. 38(3):267-9(1974)).

In some embodiments, being already treated with a serotonin enhancerminimizes side effects experienced by a subject with initiation of 5-HTPadjunct administration. Therefore, in some embodiments the subject hasbeen taking a serotonin enhancer for at least 5 days, 1, 2, 3, 4 or 5weeks, or 1, 2, 4, 6, or 12 months before the initiation of 5-HTPcoadministration.

Subjects that may be treated in accordance with the present disclosureare, in general, mammalian subjects (e.g., rodent subjects such as mouseor rat, primate subjects such as human or monkey, dog, cat, rabbit,etc.), including male and female subjects. The subject may be of anyrace and any age, including juvenile, adolescent, and adult.

“Treating” as used herein means the medical management of a subject,e.g., a human patient, with the intent to cure, ameliorate, stabilize,prevent, and/or delay the onset of a disease, pathological condition, ordisorder, or one or more symptoms thereof. “Treating” may includesubmitting or subjecting a subject to a compound which will promote thereduction of symptoms of a disease, or which will slow the progressionof said disease, alone or in combination with other indicated therapies,e.g., psychiatric therapy, dietary therapy, etc. For example, a subjectmay be treated with the administration of synthesized organic molecules,naturally occurring organic molecules, peptides, polypeptides, nucleicacid molecules, and components thereof, and/or psychiatric therapy,electroconvulsive therapy, modulation of dietary intake of amino acidssuch as tryptophan (which is metabolized into serotonin) and/or tyrosine(which is metabolized into dopamine), etc. “Treating” is also intendedto include the act of not giving a subject a contra-indicatedtherapeutic.

Subjects may be those previously determined to be non-responsive orinsufficiently responsive to treatment therapy with a serotonin enhancersuch as a serotonin reuptake inhibitor alone, for example, subjects whoexhibited no benefit or improvement in symptoms with administration of aserotonin enhancer such as a serotonin reuptake inhibitor; subjects whoexhibited insufficient benefit or improvement in symptoms withadministration of a serotonin enhancer such as a serotonin reuptakeinhibitor; or subjects who exhibited a decrease over time in benefit orimprovement in symptoms with administration of a serotonin enhancer suchas a serotonin reuptake inhibitor.

In some embodiments, subjects may be screened (e.g., genotyped) for aTph2 mutation and/or low serotonin levels, for instance by usingserotonin biomarkers (Jacobsen J. P. et al., Deficient serotoninneurotransmission and depression-like serotonin biomarker alterations intryptophan hydroxylase 2 (Tph2) loss-of-function mice. Mol Psychiatry.2011 May 3. [Epub ahead of print]), prior to initiation of thetreatments described herein. Such subjects may be more confidentlyadministered the treatments described herein based on a greaterexpectation of likely clinical benefit of these treatments, based on thegreater understanding of the underlying genetic and physiological basisof the disorder as described herein.

“Tryptophan hydroxylase 2” or “Tph2” is the brain-expressed form oftryptophan hydroxylase, which is the rate-limiting enzyme in thesynthesis of serotonin (“5-hydroxytryptamine” or “5-HT”). Tph2 consistsof an N-terminal regulatory domain, a catalytic domain and a C-terminaltetramerization domain, and belongs to the superfamily of aromaticamino-acid hydroxylases including tyrosine hydroxylase, phenylalaninehydroxylase and Tph1. Tryptophan hydroxylase functions in the body toconvert tryptophan to 5-hydroxytryptophan (“5-HTP”), which is thendecarboxylated by aromatic amino acid decarboxylase (“AADC”) toserotonin, as illustrated in the scheme presented below:

“Serotonin enhancer” as used herein refers to any compound thatincreases, directly or indirectly, the availability of serotonin in thecentral nervous system for binding to serotonin receptors at thepost-synaptic membrane, and includes, but is not limited to, serotoninreuptake inhibitors, monoamine oxidase inhibitors, tricyclicantidepressants, serotonin agonists, amphetamines, serotonin precursors,serotonin prodrugs, intermediates in the biosynthesis of serotonin,co-factors, and pharmaceutically acceptable salts thereof. Suchcompounds may be given alone or in combination with other serotoninenhancers.

If not receiving a serotonin enhancer therapy, a subject screened orgenotyped according to the present invention and found to have a Tph2variant may be administered a serotonin enhancer and/or otherappropriate treatment as a therapy for a serotonin neurotransmissiondysregulation disorder in accordance therewith. If receiving a serotoninenhancer therapy, a subject screened or genotyped according to thepresent invention may have a previously prescribed serotonin enhancertherapy adjusted and/or discontinued in favor of an alternate treatment,or adjusted to include other suitable treatments (such as 5-HTPcoadministration) in addition to the serotonin enhancer therapy.

In other embodiments, however, a subject may be administered a slowrelease 5-HTP formulation as taught here without such screening for aTph2 variant and/or low serotonin levels, particularly since the 5-HTPformulations in some embodiments show good tolerability with little tono side effects. For example, a subject currently taking a serotoninenhancer may be administered a 5-HTP formulation as taught herein todetermine whether a benefit is seen, for example if the 5-HTP can rendera treatment-resistant subject responsive to the serotonin enhancer witha small risk of side effects.

As taught herein, the 5-HTP formulation may also increase endogenousextracellular serotonin levels in the brain in subjects having normalserotonin levels. Normo-serotonergic individuals with depression maystill be treatment-resistant to serotonin enhancers despite asignificant enhancement of extracellular serotonin, for instance, butnot restricted to, if signaling via one or more serotonin receptors isdysfunctional. Therefore, in some embodiments, the subject may betreatment-resistant despite significant enhancement of extracellularserotonin levels and may be administered a 5-HTP formulation herein toenhance the effect of the serotonin enhancer, which may further increasethe extracellular serotonin levels. In other embodiments, the patient isnot treatment-resistant to serotonin enhancers, but is nonethelessco-administered 5-HTP slow release to further augment the antidepressanteffect. Similarly, a subject who does not carry a Tph2 variant and/orlow serotonin levels may be administered 5-HTP to boost the effects of aserotonin enhancer on endogenous extracellular serotonin levels in thebrain, which may aid in treatment with a small risk of side effects.

The term “S SRI” or “selective serotonin-inhibitor” refers to thosecompounds typically used as antidepressants and are associated with theincrease in the extracellular level of the neurotransmitter serotonin byinhibiting its uptake into the presynaptic cell, increasing the level ofserotonin in the synaptic cleft available to bind to the postsynapticreceptor. Example of suitable SSRIs include, but are not limited to,citalopram, dapoxetine, escitalopram, fluoxetine, fluvoxamine,indalpine, paroxetine, sertraline, vilazodone, zimelidine andcombinations thereof. In some embodiments, the SSRI is fluoxetine.

Numerous serotonin enhancers and serotonin enhancer therapies are known.See, e.g., U.S. Pat. No. 6,218,395. The serotonin enhancer can be aserotonin reuptake inhibitor, for example, a selective serotoninreuptake inhibitor (SSRI), such as described in U.S. Pat. Nos.6,552,014; 6,492,366; 6,387,956; 6,369,051; or U.S. Pat. No. 5,958,429;or U.S. Patent Application Publication Nos. 2010/0267772 to Willigers;2008/0132514 to Pinney et al.; 2007/0042014 to Cremere et al.;2003/0191126 to Kodo et al.; or 2002/0103249 to Bogeso et al. (eachincorporated herein by reference).

Examples of known serotonin reuptake inhibitors that may be used incarrying out the present invention include, but are not limited to:

-   -   cianopramine or a pharmaceutically acceptable salt thereof        (e.g., 5-[3-(dimethylamino)propyl]-10,11-dihydro-5H-dibenz[b,        f]azepine-3-carbonitrile);    -   citalopram or a pharmaceutically acceptable salt thereof (e.g.,        1-[3-(dimethylamino)propyl]-1-(p-fluorophenyl)-1,3-dihydro-isobenzofuran-5-carbonitrile);    -   escitalopram or a pharmaceutically acceptable salt thereof        (e.g.,        (S)-1-3-dimethylamino-propyl-1-(4′-fluoro-phenyl)-1,3-dihydro-isobenzofuran-5-carbonitril,        oxalate);    -   dapiprazole or a pharmaceutically acceptable salt thereof (e.g.,        5, 6, 7, 8-tetrahydro-3-[2-(4-o-tolyl-1-piperazinyl)ethyl]-1, 2,        4-triazolo[4, 3-a] pyridine (hydrochloride));    -   desvenlafaxine or a pharmaceutically acceptable salt thereof        (e.g., Phenol,        4-[2-(dimethylamino)-1-(1-hydroxycyclohexyl)ethyl]-(Z)-2-butanedioate        (1:1) monohydrate);    -   duloxetine or a pharmaceutically acceptable salt thereof,        including LY 223.332, LY264.452 ((−)-enantiomer), LY248.686        (HCl), and Y227.942 (+)-enantiomer) (e.g.,        (+)-(S)-N-methyl-(1-napthyloxy)-2-thiophenepropylamine (HCl));    -   fluoxetine or a pharmaceutically acceptable salt thereof (e.g.,        3-[(p-trifluoromethyl)phenoxy]-N-methyl-3-phenyl-propylamine        (hydrochloride));    -   fluvoxamine or a pharmaceutically acceptable salt thereof (e.g.,        (E)-5-methoxy-4′-(trifluoromethyl)valerophenone        O-(2-amino-ethyl)oxime (hydrogen maleate));    -   ifoxetine or a pharmaceutically acceptable salt thereof (e.g.,        (+/−)-cis-4-(2, 3-xylyloxy)-3-piperidinol (sulfate));    -   indalpine or a pharmaceutically acceptable salt thereof (e.g.,        3-[2-(4-piperidyl)ethyl]indole);    -   LY 113.821 or a pharmaceutically acceptable salt thereof (e.g.,        N-methyl-3-(1-naphthoxy)-3-phenylpropylamine);    -   mirtazapine or a pharmaceutically acceptable salt thereof (e.g.,        1, 2, 3, 4, 10,14-hexahydro-2 methylpiprazino[2, 1-a]pyrido[2,        3-c]benzazepine);    -   nefazodone or a pharmaceutically acceptable salt thereof (e.g.,        1-[3-[4-(m-chlorophenyl)-1-piperazinyl]propyl]-3-ethyl-4-(2-phenoxyethyl)-²-1,        2, 4-triazolin-5-one (HCl));    -   2-nitroimipramine or a pharmaceutically acceptable salt thereof        (e.g.,        5-[3-(dimethylamino)propyl]-2-nitro-10,11-dihydro-5H-dibenz[b,f]azepine        (hydrochloride);    -   nortriptyline or a pharmaceutically acceptable salt thereof        (e.g., 10,11-dihydro-N-methyl-5H-dibenzo[a,        d]cycloheptene-Δ^(5,Γ) propylamine (hydrochloride));    -   paroxetine or a pharmaceutically acceptable salt thereof (e.g.,        (3S-trans)-3-[(1, 3-benzodioxol-5-yloxy)        methyl]-4-(4-fluorophenyl)piperidine));    -   RU 25.591 or a pharmaceutically acceptable salt thereof (e.g.,        cis-6, 7, 8,        9-tetrahydro-N,N-dimethyl-5-(p-nitrophenoxy)-5H-benzocyclohepten-7-amine        (fumarate));    -   sercloremine or a pharmaceutically acceptable salt thereof        (e.g., 4-(5-chloro-2-benzofuranyl)-1-methylpiperidine        (hydrochloride));    -   sertraline or a pharmaceutically acceptable salt thereof (e.g.,        (+)-cis(1S,4S)-4-(3, 4-dichlorophenyl)-1, 2, 3,        4-tetrahydro-N-methyl-1-naphthylamine (HCl));    -   setiptiline or a pharmaceutically acceptable salt thereof (e.g.,        2, 3, 4, 9-tetrahydro-2-methyl-1H-dibenzo[c, f]cyclohepta[1,        2-c]pyridine (maleate));    -   tianeptine or a pharmaceutically acceptable salt thereof (e.g.,        N-(3-chloro-6,11-dihydro-6-methyldibenzo[c,f][1,2]thiazepin-11-yl)-7-amino-heptanoic        acid S, S-dioxide);    -   trazodone or a pharmaceutically acceptable salt thereof (e.g.,        2-[3-[4-(3-chlorophenyl)-1-piperazinyl]propyl]-1, 2,        4-triazolo[4, 3-a]pyridin-3(2H)-one (hydrochloride));    -   venlafaxine or a pharmaceutically acceptable salt thereof (e.g.,        (+/−)-1-[2-(dimethylamino)-1-(p-methoxyphenyl)ethyl]cyclohexan-1-ol        (HCl))    -   viqualine or a pharmaceutically acceptable salt thereof (e.g.,        cis-6-methoxy-4-[3-(3R,4R)-(3-vinylpiperidyl)        propyl]-quinoline); and    -   zimeldine or a pharmaceutically acceptable salt thereof (e.g.,        (Z)-3-(p-bromophenyl)-N, N-dimethyl-3-(3-pyridyl)allylamine).

The serotonin enhancer can be a monoamine oxidase inhibitor (MAOI) suchas described in U.S. Pat. Nos. 6,472,423 and 6,011,054. Examples ofmonoamine oxidase inhibitors include, but are not limited, toisocarboxazid, phenelzine, tranylcypromine, and phenethylamines such asselegiline. The serotonin enhancer can be a serotonin agonist such asdescribed in U.S. Pat. Nos. 6,656,172; 6,579,899 and 6,387,907. Theserotonin enhancer can be an amphetamine, including, but not limited to,derivatives thereof such as phentermine, fenfluramine, and(+)-3,4-methylenedioxyamphetamine. The serotonin enhancer can be atricyclic antidepressant such as described in U.S. Pat. Nos. 6,368,814;6,358,944; 6,239,162; and 6,211,171. Examples of tricyclicantidepressants include, but are not limited to, imipramine,amitriptyline and clomipramine.

The serotonin enhancer can be an anxiolytic such as buspirone oripsapirone.

The serotonin enhancer can be a precursor or prodrug of serotonin, or anintermediate in serotonin biosynthesis, such as described in U.S. Pat.Nos. 6,579,899; 6,013,622; and 5,595,772. Examples include tryptophan,5-hydroxytryptophan (5-HTP), TPH2 co-factor tetrahydrobiopterin and itsprecursors, and a tryptophan-rich diet or dietary supplements oftryptophan.

The enzymatic cofactor tetrahydrobiopterin[(6R)-L-erythro-5,6,7,8-tetrahydrobiopterin (or “BH4”) may also beadministered according to some embodiments. See, e.g., U.S. Pat. Nos.6,451,788 and 4,920,122. While the present invention is describedprimarily with reference to BH4, other BH4 enhancers such as folates andanalogs thereof, (e.g., methylfolate) as well as estrogen agonists andglucocorticoid antagonists may be used in addition, or in alternative,thereto. Folate analogs are known and described in, for example, U.S.Pat. Nos. 6,808,725; 6,673,381; 6,500,829; and 6,191,133.

Vitamin B6, which is a cofactor in the conversion of 5-HTP to serotoninin the body, may also be administered, as desired.

Formulations may be provided in any suitable form, such as tablets,capsules, suppositories, inhalation or aerosolizable formulations,formulations in an inhalation delivery device, parenterally injectableformulations, etc. In the case of a neutraceutical composition, theformulation may be provided in the form of a bar, beverage, drink, snackfood, etc.

The active compounds may be administered to the subject by any suitableroute, including oral administration, buccal administration, parenteralinjection, inhalation or aerosol administration, transcutaneousadministration, etc.

The therapeutically effective dosage of any specific active compound,the use of which is in the scope of present invention, will varysomewhat from compound to compound, and patient to patient, and willdepend upon the condition of the patient and the route of delivery.

For example, a serotonin enhancer such as a serotonin reuptake inhibitorcan be administered to the average adult human for the treatment of thedisorders described herein in an amount of from about 0.1 mg to about2000 mg, preferably from about 1 mg to about 200 mg per unit dose.

A peripheral decarboxylase inhibitor such as carbidopa, benserazide ormethyldopa can, in some embodiments, be administered to an average adulthuman subject in an amount of from 5 or 10 to 25, 50 or 100 milligramsper unit dose in combination with the 5-HTP.

A precursor or prodrug of serotonin, or an intermediate in serotoninbiosynthesis, including 5-hydroxytryptophan (5-HTP), may be administeredin an amount of from about 1, 2, 5 or 10 milligrams up to 0.1, 0.5, 1 or4 grams per unit dose.

The therapeutically effective dosage may also vary depending uponwhether two or more agents are administered in combination. For example,while 5-HTP alone may have only a modest effect on depression, 5-HTP incombination with a serotonin enhancer such as an SSRI may have a potentsynergistic effect, yielding a larger increase in extracellular 5-HT ascompared to the addition of the SSRI and 5-HTP effects. Therefore, atherapeutically effective dosage of 5-HTP when administered incombination with an SSRI may in some embodiments be lower that atherapeutically effective dosage of 5-HTP alone. In addition,administration of a slow-release 5-HTP may result is a different dosage(e.g., a lower dose, or higher dose to be released over a longer periodof time) than would be effective as an immediate-release formulation.Administration of unit doses of active agents, alone or in combination,may be one or several times daily, for example 2, 3, 4 or 8 times,giving for example, 1, 2 or 3 doses each time. As used herein, theadministration of two or more agents (inclusive of serotonin enhancers)“in combination” means that the agents are applied closely enough intime that the presence of one alters the biological effects of theother. The two agents may be applied simultaneously (concurrently orcontemporaneous) or sequentially. Administrations according to someembodiments may be within a period of time that ranges from minutes(e.g., 1, 5, 10, 30, 60, or 90 minutes or more) to days (e.g., 1, 2, 5,8 or 10 or more days), as appropriate for efficacious treatment.

Simultaneous, concurrent or contemporaneous administration of the agentsmay be carried out by mixing the agents prior to administration, or byadministering the agents at the same point in time but different routesof administration, or applied at times sufficiently close that theresults observed are indistinguishable from those achieved when thecompounds are applied at the same point in time.

Sequential administration of the agents may be carried out byadministering one agent at some point in time prior to administration ofa second agent, such that the prior administration of one alters orenhances the effects of the other, or vice versa.

“Enhance the activity of” as used herein means the agent (a) increasesthe treatment efficacy of an otherwise efficacious agent to an even moreefficacious level; or (b) increases the treatment efficacy of anotherwise ineffective active agent to an efficacious level.

Biomarkers may also be detected and/or monitored as appropriate ordesired, and may be used to detect an imbalance in monoamineneurotransmitters such as serotonin, catecholamines (e.g., dopamine,epinephrine and norepinephrine), etc. Biomarkers can be measure in abiological sample such as blood, cerebrospinal fluid (CSF), or urine.These biomarkers include, but are not limited to, metabolites such as5-HIAA, homovanillic acid, and vanillylmandelic acid. For example,decreased cerebrospinal fluid (CSF) levels of 5-hydroxyindoleacetic acid(5-HIAA), the main metabolite of serotonin, may be measured and/ormonitored to probe serotonin levels in the body. Detection of elevated5-HIAA (and, optionally, detection of low homovanillic acid and/orvanillylmandelic acid) may indicate a neurochemical imbalance due toelevated serotonin. Such elevated serotonin may contraindicate treatmentwith a serotonin enhancer such as an SSRI and/or 5-HTP. Homovanillicacid is a catecholamine metabolite and is associated with dopaminelevels in the brain. Similarly, vanillylmandelic acid is a metabolite ofthe catecholamines epinephrine and norepinephrine.

Altered 5-HT receptor responses are known to be associated withdepression and suicidality, e.g.

5-HT_(2A),

5-HT_(1A). Hypothermic responses to 5-HT receptor agonists (e.g.,5-HT_(1A) receptor agonists) may also be measured and/or monitored asknown in the art. For example, measurement of the hypothermic responsein response to 5-HT_(1A) receptor agonists is known. See, e.g., Rauschet al., “Temperature Regulation in Depression: Functional 5HT1A ReceptorAdaptation Differentiates Antidepressant Response,Neuropsychopharmacology, 2006, 31:2274-2280. Examples of 5-HT_(1A)receptor agonists include, but are not limited to, 8-OH-DPAT,alnespirone, AP-521, buspar, buspirone, dippropyl-5-CT, DU-125530,E6265, ebalzotan, eptapirone, flesinoxan, flibanserin, gepirone,ipsapirone, lesopitron, LY293284, LY301317, MKC242, R(+)-UH-301,repinotan, SR57746A, sunepitron, SUN-N4057, tandosporine, U-92016A,urapidil, VML-670, WAY-100635, zalospirone or zaprasidone.

Decreased prolactin or cortisol response to a 5-HT releaser (e.g.,fenfluramine) may also be measured, as desired. Other signs or symptomswhich may be considered and/or monitored include the presence of normalworking memory but deficits in recognition and recall memory, which areknown to be associated with serotonin dysregulation disorders such asdepression in humans.

The present invention is explained in greater detail in the followingnon-limiting Examples.

Example 1

The effect of 5-HTP administration was tested in wild-type and 5-HTdeficient Tph2KI (R439H) mice. Administration of 5-HTP by providing5-HTP in drinking water (4 mg/ml≈320 mg/kg/day, no carbidopa) robustlyrestored brain 5-HT in 5-HT deficient mice towards normal (FIG. 1).

There was a body weight decrease observed after 5-HTP 4 mg/ml (FIG. 2),but it seems to be related to decreased drinking (FIG. 3). No diarrheaand no obvious malaise were observed (data not shown).

Bolus injection of 5-HTP 120 mg/kg i.p., however, caused diarrhea (FIG.4) and obvious malaise (data not shown).

Administration of 5-HTP as an adjunct to serotonin enhanceradministration was also tested by using (≈200 mg/kg/day) 5-HTP as anadd-on to existing chronic fluoxetine administration (≈18 mg/kg/day). Noindication of toxicity was observed (weights, head twitches, diarrhea)(FIG. 5), illustrating the feasibility of adding on 5-HTP slow-releaseto existing SSRI treatment.

In contrast, administration of an acute 5-HTP bolus (80 mg/kg, i.p.) asan add-on to existing fluoxetine (FLX) (≈18 mg/kg/day) resulted in 5-HTsyndrome-like behavior (FIG. 6). However, FLX unexpectedly seems todecrease diarrhea induced by 5-HTP (FIG. 6), although not rigorouslytested in this experiment.

In summary, it was found that continuous oral, high-dose 5-HTP restorestissue 5-HT levels under conditions of 5-HT deficiency. Carbidopa wasnot necessary for the effect.

Bolus 5-HTP administration caused gastrointestinal side effects in themice. Continuous 5-HTP administration, however, did not result ingastrointestinal side effects.

These data on coadministration of continuous/slow-release 5-HTP as anadd-on to FLX indicates that this combination is not toxic and does notresult in side effects. This finding contrast to common beliefs amongindividuals skilled in the art, the laity and recommendations fromgovernment agencies, i.e. NIMH. Bolus/immediate release 5-HTP, however,causes 5-HT syndrome in FLX-treated mice.

Example 2

Potentially, selective serotonin reuptake inhibitor (S SRI) effects onextracellular serotonin (5-HT_(Ext)), and hence the clinical effect,could be enhanced by co-administration of 5-HTP (the immediate precursorof 5-HT). This could particularly apply to, but not be restricted to,patients with low endogenous brain 5-HT, for instance caused bydecreased brain Tph2 catalytic function. 5-HTP per se may have poordrugability, however. 5-HTP has fast-in-fast-out kinetics, often causingside-effects upon ingestion even at moderate doses (e.g.,gastro-intestinal disturbances, dizziness) and short time of action(Gijsman et al., Placebo-controlled comparison of three dose-regimens of5-hydroxytryptophan challenge test in healthy volunteers. J ClinPsychopharmacol 22, 183 (April, 2002); Lowe et al.,L-5-Hydroxytryptophan augments the neuroendocrine response to a SSRI.Psychoneuroendocrinology 31, 473 (May, 2006). Thus, 5-HTP asaugmentation for SSRIs could be associated with cycling betweenside-effects/overdose and drug-withdrawal as well as suboptimal overallexposure.

However, administering 5-HTP as a slow release (SR) formulation couldameliorate 5-HTP's poor drugability by i) decreasing absorption rate;ii) decreasing peak levels, iii) prolonging exposure time, iv) enhancingtotal exposure and v) facilitating patient compliance. Thus, formulating5-HTP as an SR formulating could transform 5-HTP into a more clinicallyuseful medication and greatly improve 5-HTP's therapeutic potential.

In this study, the potential of add-on of 5-HTP SR to augment the5-HT_(Ext) response to chronic fluoxetine (FLX, an SSRI) was assessed inTph2 R439H mice, a naturalistic and clinically relevant model ofendogenous 5-HT deficiency (Jacobsen et al., Deficient serotoninneurotransmission and depression-like serotonin biomarker alterations intryptophan hydroxylase 2 (Tph2) loss-of-function mice. MolecularPsychiatry (May 3, 2011); Beaulieu et al., Role of GSK3 beta inbehavioral abnormalities induced by serotonin deficiency. Proceedings ofthe National Academy of Sciences of the United States of America 105,1333 (2008)).

Methods Experiment #1:

Wild type and Tph2 R439H mice were treated for >3 wks with a saturatingdose of FLX (155 mg/L drinking water, ˜20 mg/kg/day) or left untreated(water) and 5-HT microdialysis was performed as described in Jacobsen, JP R et al. (Deficient serotonin neurotransmission and depression-likeserotonin biomarker alterations in tryptophan hydroxylase 2 (Tph2)loss-of-function mice. Molecular Psychiatry (May 3, 2011)). Briefly:

Materials:

Escitalopram was a generous gift from Lundbeck (Valby, Denmark).Dexfenfluramine, 8-OH-DPAT, DOI, 5-HT, 5-hydroxytryptophan (5-HTP),5-HIAA, 3,4-dihydroxyphenylacetic acid, homovanillic acid and clonidinewere purchased from Sigma (St. Louis, Mo., USA). NAN-190 and DPCPX werepurchased from Tocris (Ellisville, Mo., USA). [¹²⁵I]p-MPPI was obtainedfrom Perkin Elmer (Waltham, Mass., USA). [³H]WAY100635, [³H]ketanserin,[³H]citalopram and [³⁵S]GTPγS were purchased from Perkin Elmer. Allother reagents used were of analytic grade. All drugs were administeredin a volume of 10 ml kg⁻¹ in saline, intraperitoneal (i.p.) orsubcutaneous (s.c.), as indicated.

Microdialysis:

Mice were anesthetized by ketamine/xylazine (100 and 10 mg kg⁻¹,respectively, in saline, i.p) and a guide cannula (CMA7, CMAMicrodialysis, Chelmsford, Mass., USA) was stereotactically implantedinto the frontal cortex (AP: 2.3 mm, ML: 0.3 mm, DV: 0.7 mm),hippocampus (AP: −3.3 mm, ML: 3.0 mm, DV: 1.5 mm) or lateral ventricle(AP: 0.3 mm; ML: 0.9 mm; DV: 2.0 mm) according to the atlas by Franklinand Paxinos (see, e.g., Franklin, K. and Paxinos, G. The Mouse Brain inStereotaxic Coordinates. Academic Press: San Diego, 1997) and fixed inplace with two anchor screws (CMA) and carboxylate dental cement (CMA).Operated mice were singly housed, treated with antibiotics (1.2 mgsulfamethoxazole ml⁻¹ and 0.24 mg trimethoprim ml⁻¹) in the drinkingwater and allowed to recover 48-96 h post-surgery.

Dialysate Collection:

The microdialysis probe was inserted into the guide cannulaapproximately 16 h before the start of sample collection to allow forthe stabilization of 5-HT_(Ext) levels. It has been previouslydemonstrated that dialysate analyte levels are usually only influencedby the tissue trauma caused by probe insertion for a few hours and thatthe blood-brain barrier is usually not compromised in brainmicrodialysate experiments (Chaurasia, C S et al. (2007) J. Clin.Pharmacol. 47:589-603). However, we employed a relatively long(overnight) stabilization period to ensure that we reached stablebaseline 5-HT_(Ext) levels unaffected by peripheral (that is, Tph1derived) 5-HT. In confirmation of the neuronal origin of the dialysate5-HT, the 5-HT_(1A)R agonist 8-OH-DPAT (1 mg kg⁻¹, i.p.) decreased5-HT_(Ext) by approximately 50%, a decrement that is within the rangetypically reported after 8-OH-DPAT administration (Li, Q. et al. (1999)J. Pharmacol Exp Ther 291:999-1007; Rossi, D. et al. (2008) J Neurochem105:1091-1099). The mouse was gently restrained and the microdialysisprobe (CMA7 7/2 for frontal cortex and hippocampus, CMA7 7/1 for lateralventricle) was inserted into the guide cannula. The mouse was thenplaced in a circular chamber with bedding, chow and water available. Atwo-channel swivel (cat. no. 375/D/22QM; Instech, Plymouth Meeting, Pa.,USA) allowed for unimpeded movement of the mouse. Artificial CSF (147 mMNaCl, 2.7 mM KCl, 0.85 mM MgCl₂, 1.2 mM CaCl₂, CMA) was delivered at aflow rate of 0.45 μl min⁻¹ from probe insertion until the end ofexperiment. Following the stabilization period, samples (30- or 120-minsample duration, as noted) were collected on ice in the dark,immediately frozen on dry ice and stored at −80° C. Dialysates wereanalyzed off-line by high-performance liquidchromatography-electrochemical detection (HPLC-EC) for 5-HT, 5-HIAA,3,4-dihydroxyphenylacetic acid and homovanillic acid, or by the SymDAQHPLC-tandem-mass spectrometry technology for simultaneous determinationof monoamines and amino acids.

Tissue 5-HT Analysis:

Frontal cortex and hippocampus were rapidly dissected and frozen on dryice. Tissues were homogenized by sonication in 20 volumes of ice-cold100 mM HClO₄. The supernatants were recovered and passed through 0.2 μmfilters and 5-HT quantified in the filtrates by HPLC-EC.

Experiment #2:

Tph2 R439H mice (˜25 g) were treated for >3 wks with a saturating doseof FLX (155 mg/L drinking water, ˜20 mg/kg/day). Thereafter Alzet 2001minipumps (1 μl solvent delivered/hr) containing a 5-HTP solution (100mg/ml, ˜100 mg/kg/day) or only vehicle was implanted (scc.) and 5-HTmicrodialysis performed at day 5 after pump-implantation. Minipumpsdeliver a constant flow of solvent from a reservoir and hence mimic theeffect of an SR formulation.

Experiment #3:

Tph2 R439H mice (˜25 g) were treated for >3 wks with a saturating doseof FLX (155 mg/L drinking water, ˜20 mg/kg/day). Thereafter Alzet 2001minipumps (1 μl delivered/hr) containing a 5-HTP solution (100 mg/ml,˜100 mg/kg/day) or only vehicle was implanted using isofluraneanesthesia, allowing for swift awakening, and the mice monitored forsigns of 5-HT syndrome hourly for 8 hrs and at 24 hrs. Splaying(0=absent, 1=present, 2=severe), head twitch (#/min) and signs ofhyperventilation (0=absent, 1=present, 2=severe) was scored. Bodyweights—a general index of toxicity—were followed for 2 days prior toand 5 days after pump implantation.

Results Experiment #1:

WT mice showed a robust increase in 5-HT_(Ext) in response to chronicFLX. As previously reported, Tph2 R439H mice had much lower baseline5-HT_(Ext), and following FLX the 5-HT_(Ext) levels were only enhancedto levels slightly below baseline levels in WT mice (FIG. 7).

Experiment #2:

Five days add-on of 5-HTP SR in the delivered dose (˜100 mg/kg/day) tochronic FLX in Tph2 R439H mice produced a 8-fold increase in 5-HT_(Ext),as compared to FLX+vehicle treated mice (FIG. 8), bringing the5-HT_(Ext) close to levels seen in FLX treated WT mice (FIG. 7).

Experiment #3:

5-HTP SR in the delivered dose (˜100 mg/kg/day) produced no signs oftoxicity, i.e. body weight changes of the first 4 days of treatment or5-HT syndrome-like behaviors upon treatment initiation (FIG. 9).

Conclusion.

The presented data demonstrate that 5-HTP SR add-on can greatly augmentthe 5-HT_(Ext) response to chronic SSRI treatment in a mammalianorganism harboring a Tph2 enzyme with low catalytic activity, in thiscase Tph2 R439H. Further, 5-HTP SR add-on in the delivered dose (˜100mg/kg/day) had no discernible toxic effects. Thus, 5-HTP SR add-on tochronic S SRI treatment may represent a viable treatment augmentationstrategy in depression and in other diseases related to dysfunction of5-HT or being treatable with 5-HTergic drugs, such as anxiety, pain anddrug abuse.

Example 3

The goal of these studies is to provide a formulation of 5-HTP as aslow-release formulation that will fundamentally improve the drugabilityof 5-HTP, transforming a natural substance with limited clinicalapplication into an effective drug with wide applicability.

Additional studies showed that 5-HTP SR administered subcutaneously (100mg/kg/24 h) will boost extracellular serotonin (5-HT) (5-HT_(Ext)—the“active” 5-HT) beyond the levels that the SSRI fluoxetine (FLX, prozac)can produce in WT and 5-HT deficient Tph2 R439H mice. This importantfinding indicates that 5-HTP SR add-on to FLX can boost 5-HT_(Ext)beyond the effect of FLX alone in subjects with normal as well asdecreased 5-HT levels (Note differences in y-axis scales).

The subcutaneous minipump mode of delivery applied here emulates wellthe transdermal mode of administration since 5-HTP in both instances isabsorbed via the skin and underlying tissue, bypassing the significant(˜50%, (Shindo H et al. Mechanism of intestinal absorption and brainuptake of L-5-hydroxytryptophan in rats, as compared to those ofL-3,4-dihydroxyphenylalanine. Chem Pharm Bull (Tokyo). June;25(6):1417-25. (1977))) first-pass metabolism of 5-HTP in the intestine.

As shown in FIG. 10, subcutaneous administration of 5-HTP SR robustlyaugmented the 5-HT_(Ext) response to chronic FLX in WT and 5-HTdeficient Tph2KI. These data support 5-HTP SR as an add-on treatment toSSRIs.

Interestingly, while the fold increase was higher in Tph2KI than in WTmice, seven- vs two-fold, the numerical increase was larger in WT micethan in Tph2KI mice, Δ18 vs Δ6 fmol/sample. The minipump-approachsecures a stable 5-HTP delivery, though the treatment duration islimited to subchronic and the dose by the reservoir size. As is shown inFIG. 11, there was virtually no side-effects associated with theminipump paradigm. Thus, the therapeutic ceiling was not reached, and astronger 5-HTP SR augmentation of FLX-induced 5-HT_(Ext) seems feasible.

Also, 5-HTP SR boosts tissue levels of 5-HT, i.e., “storage” of 5-HT.The 5-HT and 5-HIAA tissue data were collected from mice not treatedwith FLX because SSRIs per se affects tissue 5-HT and 5-HIAA levels.5-HTP SR in the applied minipump paradigm robustly increased 5-HT andthe metabolite 5-HIAA, as would be expected from the robust effects on5-HT_(Ext). For 5-HTP IR, it was measured 8 h after last injection(total of 9 over 5 days) as a reasonable quasi-approximation for theaverage 5-HT and 5-HIAA levels administrations.

METHODS: 5-HT Microdialysis 5-HTP SR. K⁺ depolarization was inducedlocally by adding 100 mM K to the perfusate. A)+B) Mice on >2w FLX (155mg/L water, ˜20 mg/kg/d) were implanted with Alzet 2001 minipumps (200ul reservoir) with vehicle (50% DMSO) or 100 mg/ml 5-HTP yielding ahourly (daily) dose of ˜4.2 (100 mg)/kg for a ˜25 g mouse andmicrodialysis performed at day 5 of vehicle/5-HTP treatment. C)Microdialysis were performed on mice after >2w FLX. 5-HT_(Ext) indialysates was determined by HPLC-EC.D). Tissue 5-HTP SR: D) Mice wereimplanted with Alzet 2001 minipumps with vehicle (50% DMSO) or 100 mg/ml5-HTP yielding a hourly (daily) dose of ˜4.2 (100 mg)/kg for a ˜25 gmouse. On day 5 following pump implantation, the mice were euthanizedand tissue collected at 5 PM. Tissue 5-HTP IR: E) Mice were injected AMand PM with 5-HTP SC 50 mg/kg or vehicle (saline) for 4 days. On day 5only at AM and euthanized 8 h later (5 PM) and tissue collected. Tissue5-HT and 5-HIAA: HPLC-EC. Statistics: T-test.

Note, the dose of FLX we use is quite high, yielding plasma levels ˜10×the clinical, meaning that the serotonin transporter is completelyoccupied and blocked, and higher doses of FLX alone would not give ahigher 5-HText response. Thus, the 5-HTP SR+FLX combo produces higher5-HT_(Ext) than FLX monotreatment appears to be capable of.

Side effects where 5-HTP SR was added to FLX were minimal (FIG. 11). SC5-HTP SR was well tolerated at the used dose, ˜100 mg/kg/d, the samethat robustly boosted the 5-HT_(Ext) response to chronic FLX. The onlysignificant side effect was a minor and transient weight loss in theTph2KI mice. Weigh loss is a common effect in rodents of 5-HTergics.Head-twitches could not meaningfully be scored because the presence ofthe SC pump itself caused twitches. Thus, a regimen of 5-HTP SR add-onto SSRIs that augments the 5-HT_(Ext) response (FIG. 10) is associatedwith virtually no obvious side-effects. The combined data from presentedin FIG. 10 and FIG. 11 supports 5-HTP SR as an add-on to SSRIs as anaugmentation strategy in disorders treatable with SSRIs such asdepression.

METHODS: Mice on >2w FLX (155 mg/L water, ˜20 mg/kg/d) were implantedwith Alzet 2001 minipumps with vehicle (50% DMSO) or 100 mg/ml 5-HTPyielding a hourly (daily) dose of ˜4.2 (100 mg)/kg for a ˜25 g mouse.Side-effect parameters were assessed between 30 min and 8 h followingpump implantation under brief isoflurane anesthesia (day1) and thendaily (day2-4). On day5 mice underwent the open field test. Diarrhea:Mice where placed individually in a cage with filter paper and thediarrhea level scored, 0-3. Tremor and splaying: Scored in home cagefrom 5 min videos. Temperature: Recorded by digital rectal temperatureprobe in lightly restrained mice. Open field: The mice were placed in an40×40 cm open field equipped with photocell panels in three dimensionsfor 30 min Center time yields an index of anxiety/agoraphobia.Statistics: Genotypes were analyses separately, with 2way RM-ANOVA ort-test as appropriate, and in the former case followed by Bonferronipost-hoc test.

In contrast, there were marked 5-HT associated side effects uponadministration when 5-HTP was given as immediate release (IR) as twodaily doses of 50 mg/kg subcutaneously (FIG. 12). SC 5-HTP IR 50mg/kg/day, the first of two daily doses, was poorly tolerated, causingpronounced 5-HT syndrome-like behaviors. Interestingly, 5-HTP IRappeared to produce more pronounced side-effects in Tph2KI mice for someparameters, i.e., tremor, splaying, head-twitches and open fieldbehaviors, while for diarrhea and hypothermia WT mice seemed moresensitive.

METHODS: Mice on >2w FLX (155 mg/L water, ˜20 mg/kg/day) were injectedAM and PM with SC 5-HTP IR (i.e. bolus) 50 mg/kg or vehicle (saline).Side-effects were assessed after the AM dose, day1-4. Diarrhea: Micewere placed individually in a cage with filter paper and the diarrhealevel scored, 0-3, 0-15 min after injection. Tremor, splaying andhead-twitch: Scored in home cage from 5 min videos, 25-30 min afterinjection. Temperature: Recorded by digital rectal temperature probe inlightly restrained mice 30 min after injection. Open field: On day5, themice were injected and immediately placed in an 40×40 cm open fieldequipped with photocell panels in three dimensions for 30 min. Centertime yields an index of anxiety/agoraphobia. Statistics: Genotypes wereanalyzed separately, with 2way RM-ANOVA or t-test where appropriate, andin the former case followed by Bonferroni post-hoc test.

When 5-HTP SR is administered orally (in drinking water), serotoninbrain tissue levels are enhanced with no apparent side effects (FIG.13). This demonstrates that oral 5-HTP reaches the brain and enhances5-HT levels. Oral 5-HTP SR ˜250 mg/kg/day was well tolerated andincreased 5-HT storage, robustly in Tph2KI mice, but only minorly in thehippocampus of WT mice. The 5-HT and 5-HIAA augmentation is likelyunderestimated since mice drink more at night, 5-HTP has a short T½ andtissue was collected at noon. Likely, quite higher doses of 5-HTP couldbe administered if not for 5-HTP's aversive taste, and higher 5-HTPconcentrations inhibited drinking (in pilots). Diarrhea was notspecifically scored, but none was noted. Thus, orally ingested 5-HTPwill boost brain 5-HT levels, with no apparent side effects.

METHODS: 5-HTP (2 mg/L) was dissolved in (1 mg/L) saccharin-H2O,administered in blackened bottles and changed twice weekly. HPLC pilotexperiments demonstrated that 5-HTP was stable for weeks in H2O at RT.Body weights and drinking per cage was followed throughout and 5-HTPconsumed estimated here from. Open field: At day14 all mice were testedfor 60 min in a novel open field 40×40 cm for locomotor activity. Tissue5-HT and 5-HIAA: HPLC-EC.

Example 4

A patient taking a selective serotonin reuptake inhibitor (S SRI) formore than 3-8 weeks, or whatever is deemed necessary by the attendingphysician to establish insufficient response, is still experiencingsymptoms of depression. The patient is administered an oral tablet, or apatch for transdermal administration, of slow-release 5-HTP to takeeither concurrently with the SSRI, at the same time of day or adifferent time of the day. The patient is periodically monitored foreffectiveness of the treatment and/or the occurrence of side effects.

Dosage of the 5-HTP may be adjusted as deemed appropriate, typicallystarting with a lower dose, for instance 100-500 mg/day for oraladministration on treatment-initiation, and subsequently increased ifneeded up to several grams per day. For transdermal administration, anexample is 25 mg/day to start, and subsequently increased up to 1gram/day.

Other drugs approved for add-on to SSRIs in depression, i.e. theatypical antipsychotics aripiprazole and quetiapine, appear to work byincreasing 5-HT_(Ext) beyond the levels achieved by the SSRI per se.However, slow-release 5-HTP has a distinct mechanism of action, namelyincreasing the endogenous 5-HT levels available for release, while theatypical antipsychotics rely on existing endogenous 5-HT production.5-HTP slow-release may, therefore, treat additional segments ofdepression patients, for instance patients with low endogenous 5-HTproduction, due for instance to low Tph2 function or other impairmentsin 5-HT homeostasis. Thus, slow-release 5-HTP could display a widerefficacy because the 5-HTP slow-release principle is not limited byendogenous 5-HT production.

The foregoing is illustrative of the present invention, and is not to beconstrued as limiting thereof. The invention is defined by the followingclaims, with equivalents of the claims to be included therein.

1. A method of treating a subject for a serotonergic neurotransmissiondysregulation disorder, wherein said subject in being treated with aserotonin enhancer, comprising administering to said subject5-hydroxytryptophan (5-HTP) at a slow rate in combination with saidserotonin enhancer, said 5-HTP administered in an amount effective toenhance the effects of the serotonin enhancer, to thereby treat theserotonergic neurotransmission dysregulation disorder.
 2. The method ofclaim 1, wherein said 5-HTP is provided in an amount effective toincrease extracellular levels of serotonin in the brain as compared tothe levels upon serotonin enhancer treatment without the 5-HTPadministration.
 3. The method of claim 1, wherein said serotoninenhancer is selected from the group consisting of serotonin reuptakeinhibitors, monoamine oxidase inhibitors, tricyclic antidepressants,serotonin agonists, amphetamines, serotonin precursors, serotoninprodrugs, intermediates in the biosynthesis of serotonin, andpharmaceutically acceptable salts thereof.
 4. The method of claim 1,wherein said serotonin enhancer is a selective serotonin reuptakeinhibitor (SSRI).
 5. The method of claim 1, wherein said serotoninenhancer is selected from the group consisting of: citalopram,dapoxetine, escitalopram, fluoxetine, fluvoxamine, indalpine,paroxetine, sertraline, vilazodone, zimelidine and combinations thereof.6. The method of claim 1, wherein said serotonin enhancer comprisesfluoxetine.
 7. The method of claim 1, wherein said subject has beentreated with the serotonin enhancer for at least 2 weeks.
 8. The methodof claim 1, wherein said 5-HTP is administered as a slow-releaseformulation.
 9. The method of claim 1, wherein said 5-HTP isadministered as a sustained release formulation.
 10. The method of claim1 in which said 5-HTP is administered such that the Tmax of said 5-HTPoccurs between 2 hours and 8 hours after said administering step. 11.The method of claim 1 in which said 5-HTP comprises a half-life ofbetween 4 to 24 hours after administration.
 12. The method according toclaim 11, wherein the half-life of said 5-HTP is between 8 and 24 hours.13. The method of claim 1, wherein said disorder is depression, anxiety,suicidality, obsessive compulsive disorder, or ADHD.
 14. The method ofclaim 13, wherein said disorder is depression.
 15. The method of claim13, wherein said disorder is major depressive disorder.
 16. The methodof claim 13, wherein said disorder is treatment-resistant depression.17. The method of claim 1, wherein said subject has a tryptophanhydroxylase 2 (Tph2) variant and/or low endogenous serotonin in thebrain.
 18. The method of claim 1, wherein said subject has not beendetermined to have low endogenous serotonin in the brain.
 19. The methodof claim 1, wherein said administering is subject to the proviso thatthe subject is not concurrently administered a peripheral decarboxylaseinhibitor in an amount effective to reduce peripheral degradation ofsaid 5-HTP.
 20. The method of claim 1, wherein said 5-HTP is provided ata rate of from 0.1 to 8 grams per day.
 21. The method of claim 1,wherein said administering step is carried out by transdermaladministration.
 22. A patch comprising: a) a backing; and b) a druglayer comprising 5-hydroxytryptophan (5-HTP), or a pharmaceuticallyacceptable salt or prodrug thereof; said patch configured to administersaid 5-HTP transdermally.
 23. The patch of claim 22, wherein said patchis a single-layer drug-in-adhesive patch, a multi-layer drug-in-adhesivepatch, a reservoir-type patch, a matrix-type patch or a monolithicpatch.
 24. The patch of claim 22, wherein said patch further comprises arelease liner.
 25. The patch of claim 22, wherein said patch isconfigured to administer 5-HTP transdermally at a rate of from 0.01 to 5grams per day.